A total number of 167,274 births were observed on birth defects in rural areas 1968-1990 in China. The results showed that there were 361 cases of neural system defects, accounting for 31.45% in all birth defects. The incidence of neural system defects was 2.19% with hydrocephalus, anencephalus and spinal bifida 0.89%, 0.87%, 0.36% respectively. The distribution of neural system birth defects showed that incidence in northern part of the country was higher than that of in the south while in winter--spring was higher than in summer--autumn. Results of unconditional logistic regression analysis demonstrated that risk factors were related to neural system defects as maternal education level, parity, delivery mode and lower birth weight.